Chromium-free conversion coating
AssigneeThe Boeing Company
InventorsFrancisco Jesus Cano-Iranzo, Uxoa Izagirre-Etxeberria, Oihana Zubillaga-Alcorta, Patricia Santa Coloma-Mozo, Nieves Lapeña-rey
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Abstract
A chromium-free conversion coating is prepared by the addition of inorganic salts to dispersions of conducting polymers which are then exposed to alloys of aluminum or other metals. Advantageously, the performance of the coating is comparable to that of known Cr (chromium)-based methods for a number of aluminum alloys having particular significance in the manufacture of aircraft.
Claims18
A process for treatment of metallic surfaces, the process comprising the steps of:
- pretreating the metallic surfaces;
- coating the metallic surfaces with a conversion coating by contacting the metallic surfaces with a conducting polymer dispersion consisting of a conducting polymer selected from the group consisting of polyaniline (PANI), polyethylenedioxythiophene (PEDOT) and polypyrrole (PPY) and inorganic metallic salts selected from at least one of molybdenum, magnesium, zirconium, titanium, vanadium, cerium, hafnium, silicon, aluminum, boron, cobalt and zinc in concentrations of the inorganic metallic salts between 2.0 grams/Liter and 20 grams/Liter and a pH value of between 1 and 6.0;
- and,
- drying the metallic surfaces.
A process for treatment of metallic surfaces on aircraft, the process comprising the steps of:
- pretreating the metallic surfaces, wherein the pretreating comprises the steps of:
- degreasing the metallic surfaces;
- cleaning the metallic surfaces;
- and,
- deoxidizing the metallic surfaces;
- coating the metallic surfaces with a conversion coating by contacting the metallic surfaces with a conducting polymer dispersion consisting of a conducting polymer selected from the group consisting of polyaniline (PANI), polyethylenedioxythiophene (PEDOT) and polypyrrole (PPY) and inorganic metallic salts selected from at least one of molybdenum, magnesium, zirconium, titanium, vanadium, cerium, hafnium, silicon, aluminum, boron, cobalt and zinc in concentrations of the inorganic metallic salts between 2.0 grams/Liter and 20 grams/Liter and a pH value of between 1 and 6.0;
- and, drying the metallic surfaces at room temperature.
A conversion coating composition for treatment of metallic surfaces, the conversion coating composition consisting of a conducting polymer dispersion consisting of a conducting polymer selected from the group consisting of polyaniline (PANI), polyethylenedioxythiophene (PEDOT) and polypyrrole (PPY) and inorganic metallic salts of at least one of molybdenum, magnesium, zirconium, titanium, vanadium, cerium, hafnium, silicon, aluminum, boron, cobalt and zinc, wherein the concentrations of the inorganic metallic salts are each between 2.0 grams/Liter and 20 grams/Liter and the pH of the conversion coating composition is between 1 and 6.0.
Dependencies are inferred from the claim text.